The present invention is generally related to an integrated circuit in which fuses for programming the integrated circuit are located so as to maximize probability of successful programming. More particularly, the present invention relates to an integrated circuit in which programming fuses are located within a predefined fuse block area separate from critical circuitry blocks.
Certain type integrated circuits must be programmed during manufacture to store chip-specific operational information necessary for the integrated circuit to function as intended when powered up for use. Such chip specific information includes, but is not limited to, redundancy programming information, clock programming information and chip serial number identification. Each piece of information may be unique to each integrated circuit manufactured.
This chip specific operational information has been stored via non-volatile programmable storage fuses. Non-volatile storage fuses are typically physically very large and require a great deal of integrated circuit real estate. Fuses are typically located and interspersed throughout the critical circuitry area of the integrated circuit near the circuitry that uses the information stored in the particular fuse. This often means that fuses are located at distant points relative to the power supply pads that feed power (current) to the integrated circuit. Further, over the years technology has made it possible to decrease the size of critical circuitry and thereby increase the density of critical circuitry for a given area of integrated circuitry real estate. However, while the density of critical circuitry has increased, the size of programmable fuses has remained largely the same. Thus, the fuse size relative to the critical circuitry that surrounds it is substantially larger. As a result, overall performance of critical circuitry is impacted as circuitry must be routed around the substantially larger programmable fuses interspersed throughout the critical circuitry area. Circuit performance is often not optimal due to the additional circuitry necessary to route signals around the adjacent programming fuses.
Electrically programmable fuses are programmed during manufacture by xe2x80x9cblowingxe2x80x9d the selected fuses within the integrated circuit to open select signal paths. During the process of blowing the selected fuses, a high current is typically delivered to the selected fuses to cause them to open (i.e. blow). Sometimes current applied to the selected fuses is not sufficient to blow the fuses thus, the programming process fails and yields the integrated circuit non-functional. Where too many fuses are being programmed (blown) at one time, the current limits of the power supply supplying the programming current may be reached or exceeded and insufficient current may be delivered to one or more of the fuses being programmed. This results in improper programming of the fuses and thus yields a non-functional integrated circuit. Further, as the location of fuses in the integrated circuit is further from the power supply pads which provide power (current) to the integrated circuit, the chance that insufficient current will be delivered to the fuse is increased. Fuses are used (read) at power-up of the integrated circuit and are not timing critical.
FIG. 1 illustrates a typical integrated circuit. There is provided a critical circuitry block 5 that contains operational circuitry not related to programming fuses, as well as fuse circuitry 11 which is interspersed throughout circuitry block 5. There is also provided power supply pads 20 by which power (current) is supplied to the integrated circuit 1 for programming and normal operation.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
The present invention provides an apparatus and method for storing chip specific operating parameters remotely from critical circuitry. Briefly described, in architecture, the system can be implemented as follows. An integrated circuit is provided which incorporates a fuse block and a critical circuitry block. The fuse block contains a programmable fuse for storing chip specific operational information. The present invention can also be viewed as providing a method for programming an integrated circuit with chip specific operational information. In this regard, the method can be broadly summarized by the following steps: receiving chip specific operating parameter information; temporarily storing said received operating parameter information; and programming said operating parameter information into a corresponding programmable storage fuse located in a fuse block on the integrated circuit.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.